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  <title>Document</title>
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  <script src="https://cdn.bootcdn.net/ajax/libs/holder/2.9.8/holder.js"></script>
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<body>
  <div class="container">
    <h2>图片</h2>
    <img src="holder.js/300x200" alt="">
    <img src="https://picsum.photos/300/200?image=2" alt="">

    <hr>
    <div class="col-xs-3">
      <img class="img-responsive" src="https://picsum.photos/500/400?image=20" alt="">
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    <div class="col-xs-3">
      <img class="img-circle" src="holder.js/200x200?bg=#a58&text=hello" alt="">
    </div>
    <div class="col-xs-3">
      <img class="img-rounded" src="holder.js/200x200?bg=#258&text=圆角" alt="">
    </div>
    <div class="col-xs-3">
      <img class="img-thumbnail" src="holder.js/200x200?bg=#258&text=圆角" alt="">
    </div>
  </div>
</body>
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